This invention relates to a magnetic recording system for writing various information signals onto a magnetic tape or a magnetic disk, and particularly to a novel magnetic recording system to realize high recording density and high reliability.
In the recording system using the magnetic tape, the combination of the magnetic tape and the magnetic head has evolved in the order of a .gamma.-Fe.sub.2 O.sub.3 coat-type tape and a ferrite head, CrO.sub.2 and a ferrite head, Co-.gamma.-Fe.sub.2 O.sub.3 and a ferrite head, metallic powder and a sendust head or amorphous head, and a CoNi evaporation tape and a sendust head or amorphous head, to achieve high density magnetic recording.
This evolution depends largely upon evolution of the magnetic recording medium. Stated differently, as the coercive force and the residual magnetic flux density of the magnetic recording medium have increased, reproduction output in a shorter wavelength region is improved. Thus, higher density is achieved.
As a novel recording system, a combination of a Co-Cr vertical magnetic recording medium and a vertical magnetic head, or a combination of a ring head and a Co-O vertical magnetic recording medium, is proposed as in the 79th Studies of Japan Applied Magnetics Institute, Reference 79-2, pages 9 to 16.
However, any of the above combinations has a problem in the rubbing surface between the magnetic tape and the magnetic head. The rubbing surface between the magnetic tape and the magnetic head does not exhibit satisfactory durability and is damaged by the medium.
Thus, the vertical magnetic recording using Co-Cr and the like has not overcome the problem in reliability for the novel magnetic recording medium.
Meanwhile, an attempt to raise the coercive force Hc of the magnetic tape in an in-plane medium is described in the 79th Studies of Japan Applied Magnetics Institute, Reference 79-2, page 15, from line 9, as follows: "By arraying acicular particles of an average coercive force of approximately 3000 Oe having similar particle diameter and size, densely and without having magnetic interaction in the longitudinal direction to have a thickness of tens of rim, information can be written with ultra high resolution of 10,000 bits/mm or higher with a bit interval of 100 nm or smaller."
However, the higher coercive force of the medium is limited by writing capability of the magnetic head.
A recording system using a magnetic head having a magnetic core composed of sendust or Co based amorphous has been conventionally employed, while it has not been conceived to raise the coercive force of the coat-type tape to 2000 Oe or higher in the magnetic recording system capable of recording and reproduction.
This is partly because the study in the field of the novel magnetic recording system is now on the Co based evaporation tape or the Co-Cr vertical magnetic recording, as seen from the above-mentioned reference publication. The coat-type medium is studied simply for lower costs and higher reliability, not for research and development of ultra high recording density media.
As described above, the study for more than a decade on the vertical magnetic recording system has not brought it to the stage of practical application to replace the Co based evaporation tape. A highly reliable magnetic recording system for a higher density has not been proposed since practical application of the Co based evaporation tape in 1989.
Since high resolution of TV picture as represented by HD-VTR increases information to be recorded, development of a magnetic recording system capable of recording with a higher density to replace the Co based evaporation tape is desired.